<template>
  <view class="uni-numbox">
    <view @click="_calcValue('minus')" class="uni-numbox__minus">
      <text class="uni-numbox--text" :class="{ 'uni-numbox--disabled': inputValue <= min || disabled }">-</text>
    </view>
    <input :disabled="disabled" @blur="_onBlur" class="uni-numbox__value" type="number" v-model="inputValue"/>
    <view @click="_calcValue('plus')" class="uni-numbox__plus">
      <text class="uni-numbox--text" :class="{ 'uni-numbox--disabled': inputValue >= max || disabled }">+</text>
    </view>
  </view>
</template>
<script>

/**
 * NumberBox 数字输入框
 * @description 带加减按钮的数字输入框
 * @tutorial https://ext.dcloud.net.cn/plugin?id=31
 * @property {Number} value 输入框当前值
 * @property {Number} min 最小值
 * @property {Number} max 最大值
 * @property {Number} step 每次点击改变的间隔大小
 * @property {Boolean} disabled = [true|false] 是否为禁用状态
 * @event {Function} change 输入框值改变时触发的事件，参数为输入框当前的 value
 */

export default {
  name: 'UniNumberBox',
  props: {
    value: {
      type: [Number, String],
      default: 1
    },
    min: {
      type: Number,
      default: 0
    },
    max: {
      type: Number,
      default: 100
    },
    step: {
      type: Number,
      default: 1
    },
    disabled: {
      type: Boolean,
      default: false
    }
  },
  data () {
    return {
      inputValue: 0
    }
  },
  watch: {
    value (val) {
      this.inputValue = +val
    },
    inputValue (newVal, oldVal) {
      if (+newVal !== +oldVal) {
        this.$emit('change', newVal)
      }
    }
  },
  created () {
    this.inputValue = +this.value
  },
  methods: {
    _calcValue (type) {
      if (this.disabled) {
        return
      }
      const scale = this._getDecimalScale()
      let value = this.inputValue * scale
      const step = this.step * scale
      if (type === 'minus') {
        value -= step
        if (value < (this.min * scale)) {
          return
        }
        if (value > (this.max * scale)) {
          value = this.max * scale
        }
      } else if (type === 'plus') {
        value += step
        if (value > (this.max * scale)) {
          return
        }
        if (value < (this.min * scale)) {
          value = this.min * scale
        }
      }

      this.inputValue = String(value / scale)
    },
    _getDecimalScale () {
      let scale = 1
      // 浮点型
      if (~~this.step !== this.step) {
        scale = Math.pow(10, (this.step + '').split('.')[1].length)
      }
      return scale
    },
    _onBlur (event) {
      let value = event.detail.value
      if (!value) {
        // this.inputValue = 0;
        return
      }
      value = +value
      if (value > this.max) {
        value = this.max
      } else if (value < this.min) {
        value = this.min
      }
      this.inputValue = value
    }
  }
}
</script>
<style lang="scss" scoped>
  $box-height: 32px;
  /* #ifdef APP-NVUE */
  $box-line-height: 32px;
  /* #endif */
  $box-line-height: 32px;
  $box-width: 32px;

  .uni-numbox {
    /* #ifndef APP-NVUE */
    display: flex;
    /* #endif */
    flex-direction: row;

    /*width: 120px;*/
  }

  .uni-numbox__value {
    background-color: $uni-bg-color;
    width: 40px;
    height: $box-height;
    text-align: center;
    font-size: 14px;
    border-width: 1px;
    border-style: solid;
    border-color: $uni-border-color;
    border-left-width: 0;
    border-right-width: 0;
		height: $box-height;
    line-height: $box-height;
  }

  .uni-numbox__minus {
    /* #ifndef APP-NVUE */
    display: flex;
    /* #endif */
    flex-direction: row;
    align-items: center;
    justify-content: center;
    width: $box-width;
    height: $box-height;
    // line-height: $box-line-height;
    // text-align: center;
    font-size: 16px;
    color: $uni-text-color;
    background-color: $uni-bg-color-grey;
    border-width: 1px;
    border-style: solid;
    border-color: $uni-border-color;
    border-top-left-radius: $uni-border-radius-base;
    border-bottom-left-radius: $uni-border-radius-base;
    border-right-width: 0;
		height: $box-height;
    line-height: $box-height;
  }

  .uni-numbox__plus {
    /* #ifndef APP-NVUE */
    display: flex;
    /* #endif */
    flex-direction: row;
    align-items: center;
    justify-content: center;
    width: $box-width;
    height: $box-height;
    border-width: 1px;
    border-style: solid;
    border-color: $uni-border-color;
    border-top-right-radius: $uni-border-radius-base;
    border-bottom-right-radius: $uni-border-radius-base;
    background-color: $uni-bg-color-grey;
    border-left-width: 0;
		height: $box-height;
    line-height: $box-height;
  }

  .uni-numbox--text {
    font-size: 16px;
    color: $uni-text-color;
  }

  .uni-numbox--disabled {
    color: $uni-text-color-disable;
  }
</style>
